I have a 96 F-150 5.8l..i had the exhaust done headers and true duals going into dual flow 40 series and dual rear exit. My Check engine light is on and it is smokin like a diesel when i floor it..and sometimes when i stop. it doesnt have cats on it. has 3 o2 sensors on it..2 on either header and one about 5 feet down the exhaust..could it be the sensors? is the anyway to bypass that if it is the sensors? Thanks for the help

First thing I thought of after i saw "I'm not running cats" is it's setting a code for a catylist inefficiency code - assuming the "one that's 5 feet down the exhaust" is a post cat sensor (when he did have the cat on)

But, if it is smoking black it's running rich, and that's probably tripping the code as well